Saturday I flew up to NY and picked up a Sterling Gray 2003 Z4 3.0i with 56k miles. Found it on Ebay a couple weeks before and after lots of talking with the owner and some research of my own, I quickly pulled the trigger. It's not a normal 3.0i though. It's got an ESS Supercharger on it.

Total engine mods bring it up to 323 whp. It's also got a limited slip from the E46 M3, had the CDV removed, the sprint booster throttle mod, adjustable front camber plates and rear control arms, and EBC slotted and dimpled rotors and pads.

Needless to say, I had a ton of fun on the way home. The car is brilliant in straight lines and curves. The instant torque that comes with a positive displacement supercharger is impossible to put into words. Oh, and it also averaged 33 mpg over the whole trip.

Couple quick picks I snapped on my droid:

I had a couple quick questions for y'all:
-The throttle is pretty soft. This makes it a bit more difficult to drive the car smoothly (the larger injectors mean there's much less travel for "normal" amounts of gas), and it means I have to wait for the gas pedal to completely return before I can shift (otherwise the revs will soar as the transmission is disengaged but the engine's still getting some gas, especially if lifting off from full throttle). Is there any quick and cheap way to give the throttle more resistance for quicker return time and easier modulation, or am I looking at a pretty extensive modification?

-If I understand it right, the biggest difference between DSC and DTC is that DSC will activate if either wheel spins, whereas DTC will only activate if both wheels spin. The Z4M's don't have DTC because of their limited slip. I'm assuming DTC is equally useless for me. Is that indeed the case, or is there something else I'm missing?

Anyways, just wanted to introduce myself. Y'all will probably be seeing me in various parts of the forum.

-If I understand it right, the biggest difference between DSC and DTC is that DSC will activate if either wheel spins, whereas DTC will only activate if both wheels spin. The Z4M's don't have DTC because of their limited slip. I'm assuming DTC is equally useless for me. Is that indeed the case, or is there something else I'm missing?

First off, congratulations on your purchase... it's nice to purchase a vehicle when you know the full history on it and get to meet the previous owner face to face.

The combination of these systems controls traction when accelerating from a stop, corner force braking (braking through a corner), individual wheel braking for traction and to control understeer or oversteer when cornering. It also modulates engine power output. ASC+T is for vehicle stability it controls all 4 wheels.

When any one or a combination of these systems are active the DSC light will blink on the dashboard in yellow. The exclamation with a circle/arrow around it.

When you press DSC for 1 second. DSC is disabled, then the DTC light remains lit on the dashboard instead. This means that ASC+T and DBC have been disabled but DTC is still active. This allows you to have limited slip/wheel spin to the rear wheels. For example if you're stuck on ice or in a snow drift, this will allow you to spin or rock the car back and forth to get out of the drift. It controls the rear wheels only in a similar fashion as a LSD. (allows limited slip then intervenes to try to ensure both wheels spin at the same rate.) Does this by using the brakes & modulating torque.

When you hold down the DSC button for 3 seconds then the DSC light comes on perminantly, DTC light is not on. This means both DSC and DTC are now disabled. Then you just have your LSD to save you.

I don't know of any way to disable DTC but keep ASC+T and DBC active.

What ratio is your M3 LSD diff? Do you know if it was just a bolt-on upgrade, hooks up to our rear subframe without any modifications?

The combination of these systems controls traction when accelerating from a stop, corner force braking (braking through a corner), individual wheel braking for traction and to control understeer or oversteer when cornering. It also modulates engine power output. ASC+T is for vehicle stability it controls all 4 wheels.

When any one or a combination of these systems are active the DSC light will blink on the dashboard in yellow. The exclamation with a circle/arrow around it.

When you press DSC for 1 second. DSC is disabled, then the DTC light remains lit on the dashboard instead. This means that ASC+T and DBC have been disabled but DTC is still active. This allows you to have limited slip/wheel spin to the rear wheels. For example if you're stuck on ice or in a snow drift, this will allow you to spin or rock the car back and forth to get out of the drift. It controls the rear wheels only in a similar fashion as a LSD. (allows limited slip then intervenes to try to ensure both wheels spin at the same rate.) Does this by using the brakes & modulating torque.

When you hold down the DSC button for 3 seconds then the DSC light comes on perminantly, DTC light is not on. This means both DSC and DTC are now disabled. Then you just have your LSD to save you.

I don't know of any way to disable DTC but keep ASC+T and DBC active.

What ratio is your M3 LSD diff? Do you know if it was just a bolt-on upgrade, hooks up to our rear subframe without any modifications?

Thanks for clearing up DSC vs. DTC.

It's got a 3.46 final drive. It is NOT a bolt on mod. It has to be machined in order to hook up to the driveshaft. Total cost (including the LSD itself) was around 4 grand according to the previous owner/receipts. He had it done by Metric Mechanic in Ohio.

So after 20k on the ESS kit, he had to replace almost all components? Something broke? or it's regular maintenance stuff? or ? How much did he spent for the replacement?

I'll probably go supercharger route when my warranty is out next year. Just trying to gauge the cost/maintenance/reliability after the kit is installed..

TIA,

Nah, he just did it to help with the sale. Supercharger components are actually pretty inexpensive. You can probably replace the whole thing for a couple hundred bucks (assuming you get them from the original manufacturers). The first time around most of the money you're spending goes toward the engineering involved in designed that exact set up, not the components themselves.

There's a near linear relationship between how high you spin a supercharger and its life. Of course, this depends on a variety of things like boost, supercharger size, etc. I'd guess the supercharger will last anywhere from 25-50k depending on the design. Like I said, it's really not expensive to replace supercharger components. The previous owner threw in practically 2/3 of what I needed to make a new one. You should probably be more worried about what the tune is doing to the engine (is it running lean/rich, how are the internals holding up, etc.). However, with the M54 is a pretty stout engine. I wouldn't be too worried about it.

Very nice! The car sounds like a beast! I'm guessing it has the ESS TS2 kit?

I ALWAYS drive in DTC mode for safety reasons. Not only does the system intervene less, but the amplitude of its intervention is also not as great. All it took was one time pulling out in traffic before I should have, gassing it, and having all torque cut ---> flashing triangle to have me learn my lesson.

Btw, you'll want to check out Tekarbon if you ever want to get the amber "hockey sticks" deleted. The car will look many years newer. They also offer angel eyes upgrades and painted housings. The car looks great as-is, but check them out if you plan on doing any cosmetic mods in the future.

One more thing - because the E46 M3 diff is speed-sensing, you may not get the full benefit unless you drive in DTC mode (allows some wheel slip). The computer may limit torque prior to the benefits of the diff being realized.

Very nice! The car sounds like a beast! I'm guessing it has the ESS TS2 kit?

I ALWAYS drive in DTC mode for safety reasons. Not only does the system intervene less, but the amplitude of its intervention is also not as great. All it took was one time pulling out in traffic before I should have, gassing it, and having all torque cut ---> flashing triangle to have me learn my lesson.

Btw, you'll want to check out Tekarbon if you ever want to get the amber "hockey sticks" deleted. The car will look many years newer. They also offer angel eyes upgrades and painted housings. The car looks great as-is, but check them out if you plan on doing any cosmetic mods in the future.

It is indeed the TS2 kit. Stage 1 with the 8.5 PSI pulley and cams. Might do intercooler and go back to the larger pulley if durability becomes an issue.

Normally, I'm not a fan of traction control. I got along just fine without it in my E36 328i. Rain, snow, whatever. As long as you know the limits of the tires in every type of condition and you understand how RWD works, you should be okay. However, with a car with double the horsepower, I'm playing it safe, ha. The throttle's much more sensitive, and the car'll spin the tires from a roll in second. I might turn it off six months from now, but I'ma take it easy until I get much more comfortable with the car.

I'm not exactly sure if the electrical side of the E46 M3 diff was preserved. It still works as you'd expect, though, so no complaints here.

I saw the tekarbon thread. I was already looking for ways to do a clear conversion. I want to do it all at once though (head lights, tail lights, side markers). It's going to be hard to find tail lights. Side markers seems like an easy DIY project, but the only place I can find tail lights at is Pelican Parts and they're a little more expensive than I'd like.